Update, 1 p.m. EDT: Fred. Olsen confirmed that Boudicca left Liverpool on schedule on 29 April for a 14-night Western Mediterranean cruise. According to a statement from the line, "During the three days the ship remained in Liverpool prior to departure, a rigorous cleansing and sanitisation programme was carried out by external specialist contractors. The Health Protection Agency and Port Health officials spent a long time onboard examining records, and speaking to management and crew. All expressed complete satisfaction with our protocols and procedures, and the way in which the company has handled this problem.

"During the course of the previous three-week cruise, there were 300 passengers affected, but all had completely recovered by the end of the cruise."

(April 22, 9 a.m. EDT) -- Fred. Olsen has cut short a cruise on Boudicca because of a suspected Norovirus outbreak, even though only six passengers remain in isolation at this stage.

The 856-passenger ship is on a 23-night cruise to the Eastern Mediterranean and sailed from Liverpool on April 6. It will now arrive back on April 27, two days early, sailing straight from Almeria to Liverpool and missing out the ports of Volos and Lisbon.

A statement from the company said: "Although there are only six passengers currently affected, Fred. Olsen has taken the decision to shorten the cruise by two days in order to allow for extensive cleaning and disinfecting to take place prior to departure on its next cruise." Boudicca is scheduled to depart Liverpool on April 29 for a 14-night voyage.

Clearly, these figures don't add up; cruise lines don't curtail cruises for six cases of Norovirus. What's happened is that there has been seasickness onboard Boudicca, with the unhappy addition of some possible cases of Norovirus.

Wendy Jeffreys, spokeswoman for Fred. Olsen, explained to Cruise Critic: "There are 786 passengers and 280 crew on board. At the very worst, we estimated that 28 percent [299 people] were sick. But this cruise has had bouts of bad weather and people were getting seasick. As numbers did appear to be escalating, and it was difficult to determine who had got what, all passengers affected were treated the same and respectfully asked to remain in their cabins. But today, only six people are still in isolation."

All passengers have been given a £100 credit to their cabin accounts to compensate for the curtailed voyage.

Fred. Olsen has had a bad run with Boudicca when it comes to Norovirus; on a cruise to the Canary Islands on December 22 last year, 286 passengers and nine crew were sick. That was the third time in less than a month that passengers had been taken ill onboard the ship; the previous two cruises in late 2009 were affected with 230 cases in total. Another ship in the fleet, Balmoral, was affected by Norovirus at the same time, with 342 cases.